Endovascular treatment has become the preferred method of repair of abdominal and thoracic aortic aneurysms, and comes with a unique complication in the form of endoleaks (type I-IV). Type II endoleaks are the focus of this review. They are the most common form of endoleak detected in CT surveillance following endovascular repair. They are observed in 9% to 30% of patients after abdominal endovascular repair (EVR), and 1.4% following thoracic endovascular aortic repair (TEVR). They are classified as primary or secondary, depending on when they are identified following EVR. Typically, retrograde filling of the aneurysm sac is caused by single or multiple, patent feeding vessels. Despite its relative frequency, there is a lack of consensus on the threshold at which treatment should be considered. The aims of treatment are to halt sac expansion or to prevent rupture. A majority of patients may be managed conservatively. In those that are treated, the most common form of management is single vessel embolization. As we will discuss here, there are several ways of performing this procedure, based on the site of endoleak, and causative vessel. Possible reasons for poor success rates will also be discussed. A general consensus on how to best manage these patients is yet to be reached. The aim of this review is to give an overview of type II endoleaks, their natural history and vessels most commonly involved, as well as different approaches to embolisation.